1. Field of the Invention
The present invention pertains to surge dampeners for use in connections with fluid conduits. In such conduits, it is frequently necessary or at least desirable to use various instruments such as pressure gauges, pH meters, conductivity probes, and flowmeters to monitor the conditions of the process fluid carried by the conduit. In many instances, however, such instruments are damaged, or at least rendered incapable of operating reliably, by the process fluid flowing through the conduit. For example, where the process fluid is being propelled by a reciprocating pump, or for numerous other reasons, the fluid flow may be characterized by pressure surges which cause extreme and/or rapid fluctuations of the instruments thereby precluding accurate readings. Such pressure surges may even damage the relatively delicate instruments. In still other instances, the process fluid itself may be harmful to the instruments, e.g., where the process fluid is an acid or other corrosive material. It is also frequently necessary to protect other apparatus such as pumps and lines from pressure surges, etc.
2. Description of the Prior Art
One method of dealing with these problems has been through the use of surge dampeners and similar protective devices. The device comprises a body having two compartments, one communicating with the process fluid conduit and the other closed and filled with either a pressurized gas or a liquid. The two compartments are separated by a flexible diaphragm.
Thus, if a pressure gauge is installed on the body of the surge dampening device in communication with the closed compartment and the compartment filled with liquid, pressure will be communicated from the conduit to the pressure gauge via the diaphragm and liquid. However, the diaphragm serves as a protective barrier between the process fluid and the pressure gauge in case the proces process is corrosive or otherwise harmful.
Where the fluid in the closed compartment of the surge dampening device is a compressive liquid, or more typically, gas, the device can be used to protect various instruments from the pressure surges. Specifically, if the surge dampening device is placed upstream of a flowmeter or other instrument in the fluid conduit, the diaphragm will expand into the closed compartment of the device when there is a pressure surge thus dampening the surge with respect to the downstream flowmeter. An instrument such as a pressure gauge communicating with the closed compartment is likewise protected.
Although such a device represents a considerable improvement in the fluid flow system, problems can still arise when the diaphragm leaks. If fluid leaks from the closed compartment, the dampening effect will be lessened. Furthermore, the nature of this fluid and the process fluid may be such that it is undesirable or hazardous to allow the two to mix in the conduit. Leakage in the other direction, i.e., from the conduit to the closed compartment, can expose the pressure gauge to any undesirable characteristics of the process fluid such as corrosiveness.